Imaging Pitfalls in Surface Bone Lesions: Florid Reactive Periostitis Mimicking Parosteal Osteosarcoma - A
Jasminka Igrec1, Nikolaus Stranger1, Marijan Puseljic1
1Medical University of Graz, Department of Radiology, Styria, Austria, Graz.
Purpose:
To evaluate imaging features and clinicopathologic correlation in florid reactive periostitis (FP) and parosteal osteosarcoma (PO), emphasizing diagnostic pitfalls in surface bone lesions.
Patients And Methods:
Four patients (two FP, two PO) underwent radiography, CT, and MRI, including dynamic contrast-enhanced sequences in selected cases. Histopathology with immunohistochemical analysis of MDM2 and CDK4, including gene amplification testing, was performed in all cases.
Results:
FP demonstrated solid or layered periosteal reaction, soft-tissue swelling, and bone marrow edema without atypia or MDM2/CDK4 amplification. PO presented as lobulated ossified masses with cortical attachment or cleavage plane and positive MDM2/CDK4 expression. DCE-MRI showed overlapping enhancement patterns and did not reliably differentiate the entities.
Conclusion:
Differentiation between FP and PO requires careful evaluation of conventional imaging features combined with histopathological confirmation. Multidisciplinary assessment remains essential to prevent diagnostic overtreatment or undertreatment.
Key Points:
· FP may mimic PO on MRI. · Cleavage plane favors parosteal osteosarcoma. · DCE-MRI shows overlapping enhancement patterns. · MDM2/CDK4 are essential in equivocal cases.
Citation Format:
· Igrec J, Stranger N, Puseljic M et al. Imaging Pitfalls in Surface Bone Lesions: Florid Reactive Periostitis Mimicking Parosteal Osteosarcoma - A Multimodality Case Series. Rofo 2026; DOI 10.1055/a-2864-1949.
